North Korea tried and failed to test-fire what appeared to be a medium-range Musudan missile on the birthday of founding leader Kim Il-Sung Friday, a high-profile misstep after Pyongyang claimed a series of breakthroughs in its nuclear weapons programme.

Military personnel pose next to a portrait of Kim Il-sung on Wednesday in Pyongyang, North Korea, ahead of birthday celebrations for the founding leader

There had been widespread intelligence reports in recent days that the North was preparing a first-ever flight test of the Musudan, believed to be capable of striking US bases in the Pacific island of Guam.

The US and South Korean militaries both detected and tracked the early morning test.

“We assess that the launch failed,” a US defence official said, adding that it was “presumably” a Musudan.

The April 15 birthday of Kim Il-Sung — the grandfather of current ruler Kim Jong-Un — is a major public holiday in North Korea, where key political anniversaries are often marked with displays of military muscle.

The country is also gearing up for a rare and much-hyped ruling party congress next month, at which Kim Jong-Un is expected to take credit for pushing the country’s nuclear weapons programme to new heights.

The failed missile launch drew criticism from North Korea’s major ally China.

“The firing of a mid-range ballistic missile on Friday by the Democratic People’s Republic of Korea (DPRK), though failed, marks the latest in a string of saber-rattling that, if unchecked, will lead the country to nowhere,” China’s official Xinhua news agency said in an English language commentary. “…Nuclear weapons will not make Pyongyang safer. On the contrary, its costly military endeavors will keep on suffocating its economy.”

A U.S. State Department official said: “We call again on North Korea to refrain from actions and rhetoric that further raise tensions in the region and focus instead on taking concrete steps toward fulfilling its international commitments and obligations.”

“Timing wise, today’s missile was a cannon salute on the Day of the Sun, leading up to the party congress, but now that it has failed, it is an embarrassment,” said Chang Gwang-il, a retired South Korean army general.